1. Field of the Invention
This invention relates to a highly conductive circuit board having a high precision by utilizing organopolysilane film and a method for preparing the same.
2. Prior Art
Organopolysilane is very interesting in that it has the metallic and electron delocalization properties of silicon in contrast to carbon, and the desirable properties of high heat resistance, high flexibility and ready adaptation to thin film formation. Highly conductive organopolysilane materials are obtained by oxidizing an organopolysilane having an amino group on a side chain with iodine or by oxidizing such an organopolysilane with ferric chloride vapor. For the purpose of developing photoresists for forming various ultrafine patterns at a high precision, active research works have been made on organopolysilane as disclosed in JP-A 72694/1993, 291273/1994, and 114188/1995. Inter alia, JP-A 72694/1993 discloses a method for preparing a semiconductor integrated circuit wherein organopolysilane optionally doped with iodine is used as a conductive layer and a siloxane layer converted from organopolysilane by light irradiation is used as an insulating layer. However, the use of corrosive iodine is an obstacle to the application of the doped organopolysilane as electronic materials. Additionally, since organopolysilane itself readily changes into siloxane by the action of atmospheric oxygen, the use of such organopolysilane as conductive material encounters difficulty in the application as electronic material where reliability is essential.
JP-A 11339/1982 discloses a method for forming a metal image by exposing a compound having a Si--Si bond to light and contacting the compound with a metal salt solution. Upon contact of a compound having a Si--Si bond with a metal salt solution, the metal salt must be reduced to a metal. This method is to form a positive metal image. An attempt was made to modify the method to the negative type so that a ultrafine image might be formed, but failed to form a precise fine circuit because the reduction of a silver salt did not quickly proceed on exposed areas of the polymer.